A load detection sensor for detecting a load on a vehicle seat by a strain member which changes the shape in accordance with an external load has been developed. According to JP2009-63494A (hereinafter referred to as Patent reference 1), a displacement detection device which can reduce a difference of an output amount from a strain detection element for detecting the change of the shape of a strain member is disclosed. The displacement detection device includes strain gauges which are attached onto the strain member receiving an output of a load input member. The strain gauges output electric signals which correspond to strain occurred by a flexure applied to the strain member in accordance with a load. The displacement detection device connects the strain member with an amplifier device by an upper bracket, a first lower bracket and a second lower bracket. According to Patent reference 1, the strain member is prevented from distorting on the basis of a welding position by welding and fixing respective outer end portions of support portions of the first lower bracket and the second lower bracket to the strain member and by welding and fixing outer end portions of an upper bracket to the strain member.
According to Patent reference 1, the strain gauges and an amplifier board are connected with one another via a flexible board. Connection portions between the strain gauges and the flexible board are protected and covered with coating portions, respectively. However, portions of the flexible board which are not covered with the coating portions may be damaged by a contact when the displacement detection device is handled by an operator, is on transportation or when being mounted to a vehicle seat. Further, the portion of the flexible board which is not covered with the coating portions may be damaged by extraneous materials.
A need thus exists for a cover for a load detection sensor and a load detection device which are not susceptible to the drawback mentioned above.